The general objective of this research is to elucidate the role of dietary fat in the metabolism of lipids in mammalian tissues. Current research is being devoted to studies of the metabolism of essential fatty acids in liver, kidney and testes and the development of improved methods of lipid extraction and analysis to facilitate these studies. This research also involves studies on the role of these fatty acids in the diet on lipid transport, lipoprotein synthesis and metabolism. A major phase of the research will be a study of the role of essential fatty acids in testicular function using hypophysectomized animals. Another objective of this project is to determine the nutritional effect of trans fatty acids in the diet. The role of these fatty acids upon the interconversion of unsaturated fatty acids and in cholesterol metabolism will be investigated.